Measurement Ontology
type: Ontology
description: The Measurement Ontology is an ontology in which measurements may be rendered.
creator: me

Measurement
type: Class
description: A measurement is a statistic that measures a quantity that may or may not have units.
subclass of: Item
subclass of: Restriction
  on property: measured quantity
  cardinality: 1

Restriction
on property: units
max cardinality: 1

Quantity
type: Class
description: A quantity is a quantifiable quality of an object.
subclass of: Dimension
disjoint with: Unit
disjoint with: Unit Class

Unit
type: Class
description: A unit is a particular quantity against which another quantity may be compared. Hence, a unit is dimensionful and provides a ratio by which a quantity may be measured.
subclass of: Dimension
disjoint with: Quantity
disjoint with: Unit Class

Unit Class
type: Restriction
type: Class
description: A unit class is a subset of units, with no particular restriction on its contents (i.e. it may be a set of units measuring orthogonal quantities, making a UnitSystem, or a set of units measuring the same quantity).
subclass of: Class
on property: subClassOf
has value: Unit
disjoint with: Quantity
disjoint with: Unit

Unit System
type: Class
description: A unit system is a class of units for which no two elements in the class measure the same dimension (i.e. all dimensions are orthogonal to each other, or measure dimensions derived from a set of orthogonal dimensions with units derived from the units that measure those orthogonal dimensions specified in the system.
subclass of: Unit Class

equivalent unit class
type: FunctionalProperty
type: ObjectProperty
description: An equivalent unit class of a quantity is the unit class corresponding to units that measure the quantity.
domain: Quantity
range: Unit Class
inverse of: measured quantity

equivalent quantity
type: InverseFunctionalProperty
type: ObjectProperty
description: An equivalent quantity of a unit class is the quantity measured by all units in the unit class.
domain: Unit Class
range: Quantity
inverse of: unitClass

measured quantity
type: FunctionalProperty
type: ObjectProperty
description: The quantity measured for a measurement.
sub property of: dimension
domain: Measurement
range: Quantity

unit
type: FunctionalProperty
type: ObjectProperty
description: The unit a measurement is made in.
sub property of: dimension
domain: Measurement
range: Unit

Area
type: Quantity
equivalent unit class: Area Unit

Area Unit
type: Unit Class
subclass of: Unit
equivalent quantity: Area

square kilometers
type: Area Unit

Area Measurement
type: Class
subclass of: Measurement
subclass of: Restriction
  on property: measuredQuantity
  has value: Area
subclass of: Restriction
  on property: unit
  has value: AreaUnit
    type: Area Unit

area
type: ObjectProperty
range: Area Measurement